Known is an electro-photographic type color printer provided with four photosensitive drums for colors of yellow, magenta, cyan, and black. Japanese Patent Application Publication No. 2009-157135 discloses such conventional color multi-function device including process cartridges for respective colors arrayed in a horizontal direction, a support frame supporting the process cartridges and can be pulled frontward from a main casing, an intermediate transfer belt, and a secondary transfer roller. Each process cartridge includes a photosensitive drum and a developing unit that includes a developing roller, a first supply roller, a second supply roller, a toner layer thickness regulation blade, and a toner container. The intermediate transfer belt extends in the horizontal direction and is positioned above and in contact with the respective photosensitive drums. The secondary transfer roller is in contact with a longitudinal end portion of the intermediate transfer belt.
Each process cartridge can be detached from and attached to the support frame in a state where the support frame is pulled out frontward from the main casing.